Apparatus and method for testing leaks

Abstract

A method and apparatus for testing leaks in a compressed natural gas fuel system on an assembly line. The apparatus includes a filling receptacle, a filling conduit, a fuel tank assembly, a supply conduit, a pressure regulating assembly, and a joint box. The filling conduit extends between the filling receptacle and the fuel tank assembly. The supply conduit extends between the fuel tank assembly and the pressure regulating assembly. The joint box includes a valve which regulates fluid communication between the filling conduit and the supply conduit. In the method according to the present invention, the tank assembly is fluidly isolated from the remainder of the fuel system and the filling conduit and supply conduit are fluidly connected, by opening the joint box valve, to permit pressurization and leak detection of a first portion of the fuel system. Thereafter, the joint box valve is closed to isolate the filling conduit from the supply conduit, and the pressure regulating assembly is activated to pressurize a second portion of the fuel system for leak detection purposes.

What is claimed is: 
     
       1. A fuel system for an automobile, comprising: a filling receptacle;   a fuel tank assembly adapted to receive and store compressed natural gas;   a filling conduit fluidly connecting said filling receptacle to said fuel tank assembly;   a pressure regulating assembly;   a supply conduit fluidly connecting said fuel tank assembly to said pressure regulating assembly; and,   a bypass operable to provide fluid communication between said filling conduit and said supply conduit.   
     
     
       2. A fuel system according to claim 1, wherein said fuel tank assembly comprises a compressed natural gas tank and a valving assembly. 
     
     
       3. A fuel system according to claim 2, wherein said valving assembly includes an input connected to said filling conduit and an output connected to said supply conduit. 
     
     
       4. A fuel system according to claim 3, wherein said valving assembly further comprises a manual inlet valve at the input and a manual outlet valve at the output. 
     
     
       5. A fuel system according to claim 3, wherein said tank assembly further comprises a solenoid valve disposed within said tank and operable to control flow through said valving assembly output. 
     
     
       6. A fuel system according to claim 3, wherein said valving assembly further comprises a relief valve operable to vent gas from said tank should pressure within said tank exceed a predetermined level. 
     
     
       7. A fuel system according to claim 1, wherein said bypass comprises a joint box, said filling conduit includes a first portion extending from said filling receptacle to said joint box and a second portion extending from said joint box to said tank assembly, said supply conduit comprises a first portion extending from said tank assembly to said joint box and a second portion extending from said joint box to said pressure regulating assembly, said joint box defining a first passageway connecting said filling conduit first and second portions, a second passageway connecting said supply conduit first and second portions, and a linking passageway interconnecting said first and second passageways. 
     
     
       8. A fuel system according to claim 7, wherein said joint box further comprises a manual valve, said valve being operable to control fluid flow through said linking passageway. 
     
     
       9. A fuel system according to claim 8, wherein said tank assembly includes a compressed natural gas tank and a valving assembly, said valving assembly including an input fluidly connected to said filling conduit second portion and an output fluidly connected to said supply conduit first portion. 
     
     
       10. A fuel system according to claim 9, wherein said valving assembly further comprises a manual inlet valve at the input and a manual outlet valve at the output, and a solenoid valve, said solenoid valve being disposed within said tank and being operable to control fluid flow through said valving assembly output. 
     
     
       11. A method for testing for leaks in an automobile fuel system, said fuel system comprising a filling receptacle, a fuel tank assembly including a fuel tank adapted to receive and store compressed natural gas, a pressure regulating assembly, a filling conduit fluidly connecting said filling receptacle to said fuel tank assembly, a supply conduit fluidly connecting said fuel tank assembly to said pressure regulating assembly, said method comprising the steps of: fluidly isolating said fuel tank from said filling conduit and said supply conduit;   fluidly connecting said filling conduit to said supply conduit;   introducing a pressurizing gas into a first portion of said fuel system;   sensing pressure in said first portion of said fuel system;   monitoring the sensed pressure for a predetermined period of time;   detecting the presence of pressurizing fluid at locations adjacent said first portion of said fuel system; and,   fluidly isolating said filling conduit from said supply conduit.   
     
     
       12. A method for testing for leaks according to claim 11, comprising the further steps of: actuating said pressure regulating assembly to introduce pressurizing fluid into a second portion of said fuel system;   detecting the presence of pressurizing fluid at locations adjacent said second portion of said fuel system.   
     
     
       13. A method for testing for leaks according to claim 11, wherein said fuel system further includes a joint box which defines a passageway which interconnects said filling conduit with said supply conduit, said joint box including a valve which is operable to regulate fluid flow through said passageway, and wherein said step of fluidly connecting said filling conduit to said supply conduit comprises opening said joint box valve and said step of fluidly isolating said filling conduit from said supply conduit comprises closing said joint box valve. 
     
     
       14. A method for testing for leaks according to claim 11, wherein said fuel tank assembly includes an inlet valve regulating fluid communication between said filling conduit and said fuel tank and a manual outlet valve regulating fluid communication between said fuel tank and said supply conduit, and wherein said step of fluidly isolating said fuel tank from said filling conduit and said supply conduit comprises closing said inlet valve and said outlet valve. 
     
     
       15. A method for testing for leaks according to claim 12, wherein said first portion of said fuel system is on an exterior of said automobile and said second portion of said fuel system is in an interior of said automobile. 
     
     
       16. An automobile having a compressed natural gas fuel system, said automobile defining an engine compartment and a tank compartment, said tank compartment having a bottom wall, said fuel system comprising a filling receptacle, a fuel tank assembly disposed within said tank compartment and adapted to receive and store compressed natural gas, a pressure regulating assembly disposed within said engine compartment, a filling conduit fluidly connecting said filling receptacle to said fuel tank assembly, a supply conduit fluidly connecting said fuel tank assembly to said pressure regulating assembly, and a bypass operable to provide fluid communication between said filling conduit and said supply conduit. 
     
     
       17. An automobile according to claim 16, wherein said bypass comprises a joint box disposed within an opening in said bottom wall and having a first side communicating with an exterior of said automobile and a second side communicating with said tank compartment, wherein said filling conduit has a first portion which extends between said filling receptacle and said joint box first side and a second portion which extends between said joint box second side and said tank assembly, and said supply conduit has a first portion which extends between said tank assembly and said joint box second side and a second portion which extends between said joint box first side and said pressure regulating assembly. 
     
     
       18. An automobile according to claim 17, wherein said joint box defines a first passageway connecting said filling conduit first and second portions, a second passageway connecting said supply conduit first and second portions, and a linking passageway interconnecting said first and second passageways, said joint box including a manual valve which is accessible from the exterior of the automobile, said valve being operable to regulate fluid flow through said linking passageway. 
     
     
       19. An automobile according to claim 18, wherein said fuel tank assembly comprises a compressed natural gas tank and a valving assembly, said valving assembly including an input fluidly connected to said filling conduit second portion, a manual inlet valve at the input, an output fluidly connected to said supply conduit first portion, an outlet valve at the output, and a solenoid valve, said solenoid valve being disposed within said tank and being operable to control fluid flow through said valving assembly output. 
     
     
       20. An automobile according to claim 19, wherein said valving assembly further comprises a relief valve operable to vent gas from said tank should pressure within said tank exceed a predetermined level.